dreds of years, and in every cubic yard
of this manured soil are millions of the germs which cause gas
gangrene and tetanus (lock-jaw) when introduced beneath the skin. If a
wound is infected with gas gangrene or other dangerous organisms, the
knowledge that they are present may materially modify the treatment
used by the surgeon, and the laboratory is of value to him sometimes
in determining that point.

The usual routine work of a hospital clinical laboratory was also
carried on by us for the casualty clearing stations in the area, and
all kinds of work from the making of a vaccine for the treatment of
bronchitis in a British General to the inoculation of a civilian child
with anti-meningitis serum came within our scope.

The hygiene work of the laboratory is also of a varied character: It
consists of the examination of water supplies, milk and foods; the
detection of poisons in water, and, occasionally, in human beings; the
evolving of methods to purify effluents discharged into streams; work
on poison gases and methods used to combat these, and many other
things.

In each division there are some sixty water carts, each of which holds
about 110 gallons. We attempted to get samples from all of these in
turn, to see whether the water had been disinfected. As all the
sources of water supply in Flanders, with few exceptions, contain
large numbers of bacteria, and as a properly chlorinated water
contains very few bacteria, it is easy to tell from a couple of simple
tests whether or not the water in the carts has been chlorinated.

As we sometimes had eight divisions in our area at one time, this
water control meant a good deal of work. The water carts were usually
to be found at the headquarters of the unit to which they belonged,
and we quickly discovered that the way to get the largest number of
water samples in the shortest time was to travel by the map up and
down the twisting narrow roads which intersected each other as though
following the trails of the original inhabitants.

It must be remembered that four or five miles behind the front line
every farm house and barn is in use most of the time for billeting
soldiers, and that these farm houses are infinitely more numerous than
they are in America. Little villages and towns are very frequent and
many of them bear the same name as other towns and villages a few
miles apart. Thus there are at least two Bailleuls, two Givenchys, two
Neuve Eglises and so on. In ou